0. Backup data and copy off Airwave server1. Install Airwave using AMP-7.6.4-x86_64.iso (this will update CentOS to version 6.2 only)Q: Will doing the above *reinstall* AMP 7.6.4 OVER the current installation, deleting all data?2. Restore backup data (depending on answer to above question).Q: Do I need to upgrade AMP to an interim version? If yes, what version?3. Upgrade AMP to version 8.2

The reinstall step of the newer CentOS version will completely overwrite your system which is why step 0 is very important. I would strongly suggest that in step 0: grab all backups from /var/airwave-backup as a precaution.

Once reinstall is complete, restore your backed up date. Once the backup is restored, make sure to check the UI to make sure the data looks consistent with how it was before.

The general rule is that you can skip 1 release in the upgrades or you can play it safe and go through each of the upgrades (7.6 -> 7.7 -> 8.0 -> 8.2). If you want to skip, you should be able to go from 7.6 -> 8.0 -> 8.2.

At that point, I'd have to run through the upgrade path again to be certain, but I think it'd still show as CentOS 6.2, but a fresh 8.2 install will have CentOS 6.6. So depending on what the cat /etc/redhat-release value is after the 8.2 upgrade, you may or may not want to repeat step 0, and then reinstall / restore once more so that you're up to date from all angles.

Another thing since you're upgrading from 2 year old code is to double check that your box is still up to spec. Several new features have been added that gobble up resources.

I did an amp_backup which creates a file called databackup.tar.gz in /alternative/. How is that file different than the nightly backups in /var/airwave-backup, and which file do I use to restore?

To clarify, the "install iso" file does a CentOS + AMP overwrite, whereas the "upgrade package" just upgrades the AMP version and (hopefully) does not overwrite data. Is that correct? If yes, wouldn't I still be on CentOS 6.2 after doing the 7.6 -> 8.0 -> 8.2 upgades?

Nightly backups are just backups from the last nightly maintenance period (see AMP Setup -> Nightly Maintenance time setting). The amp_backup script is called as a part of the nightly_maintenance routine. The difference in running amp_backup is that it will give you a closer backup point (for instance, if nightly maintenance backups are from 10pm, and it's already 10am by the time you're about to perform the process, there's a potential 12 hour extra of data loss - this may or may not be acceptable based on your requirements). Another difference is that nightly_maintenance runs in the background at a medium priority job while AMP is still available for use, while amp_backup forces the AMP to go offline to perform a relatively quicker backup).

Correct, the ISO install will reinstall the OS and then you have to do amp-install to unpackage the AMP code after the fresh install. The upgrade package doesn't include the entire OS which is why it's roughly half the size, but upgrade packages do contain updated RPMs (the version ISO would carry the same updated RPMs). So if you continue to upgrade with the upgrade package, you will be able to keep up with the latest security patches for the underlying OS.

Update server sizing guide is located on support.arubanetworks.com under documentation, software, airwave and then navigate to the proper release. For 8.2.0.2, you'd be looking at this doc link.